Piston construction



May 28, 1957 J. T. PHlPPs 2,793,921

PIs'foN CONSTRUCTION Filed March 8. 1954 2 Sheets-Sheet 1 May 2s, 1957 JT. PHIPPS 2,793,921

PIsToN CONSTRUCTION Filed March 8, 1954 2 Sheets-Shea?l 2 565 IN VENTOR.

7 CHN I 71 17H/ppg GENT.

Unite rates Patent() PISTON CONSTRUCTION .lohn T. Phipps, Wilmington,(Iaiif.

Application March 8, 19554, Serial No. 414,703

14 Claims. (Cl. 309-4) This inventionhas to do with a double actingpiston construction adapted for use in a slush pump or thelike, whereinabrasive materials or liquids, such as drilling mud, are handled orpumped under high pressure. Y

Due to the extreme pressures and abrasive nature of the uids commonlyhandled by slush pumps, conventional piston constructions are soon wornout or destroyed and must be replaced. Replacement yof ordinary orconventional piston constructions in a slush pump generallyrequires'removing o'r' pulling the piston rod from the pump, whichoperation is costly and time-consuming. Pulling of the piston rod from aslush pump for the purpose of replacing or repairing the piston thereonfurther requires removal and replacement of the packing in the stun'gbox through which the rod extends, which operation lrequires a furtherexpenditure of time and money.

'It is a general object of the present invention to provide an improveddouble acting piston construction for a slush pump or the like, that canbe quickly and easily applied to or removed from the piston` rod .andinserted into or removed from the cylinder of an ordinary slush Anotherobject of the invention is to provide a piston-Y construction of thecharacter referred to employing one,

easily replaceable, inexpensive and'highly effective and" durablewearing element.

It is another object of the invention yto provide a molded rubber pistonbody having a metallic reinforcing'.

core.

Another object is to .provide a piston cylinder engag-` ing piston bodywith suitable fluid actuated sealing lips at opposite ends thereof.

The various objects and features of my invention will be fullyunderstood from the following detailed description of a typicalpreferred form and -application off the invention, throughout whichdescription reference is made tothe accompanying drawings, in which:

Fig. l is a perspective view of a typical conventional slush pump havinga portion broken away to show the piston construction provided by thepresent invention arranged therein. Fig. 2 is a longitudinal sectionalView of the piston construction that -I provide and applied to the end.of a typical or conventional slush pump piston rod. Fig. 3 is alongitudinal sectional view of the piston construction that I providearranged -in a pump cylinder in a semi-assembled condition land having asuitable pulling tool engaged therein. Fig. 4 is an elevational view ofthe stop collar provi-ded by the present invention engaged on thetapered end portion` of atypical slush Patented May 28, 1957 ICC pumppiston rod. Fig. 5 is a sectional view of certain` of the parts of myinvention engaged with each other to form a sub-assembly of parts. Fig.6 is an exploded view of the parts forming the sub-assembly shown inFig. 5. Fig. 7 is an end elevational view taken as in- -dicated by line7-7 on Fig. 5. Fig. 8 is an end elevational view taken as indicated byline 8 8 on Fig. 5. IFig. 9 is a transverse sectional kView of thepiston body taken substantially as indicated by line 9-9 on Fig. 6.

'In Fig. l of the drawings I have shown the piston construction Aprovided by the present invention cooperatively engaged in a typicalslush pump P having an elongate pump vchest `10, a cylinder O in thechest, an elongate piston rod R' extending into the -cylinder andslidably engaged in a suitable stuing box 11 in one end of the chest,and a suitable drive means 12 spaced from the said end of the chest andoperatively connected with the rod. The pump P is further characterizedby a head 13 releasably secured to t-he other end of the chest bysui-table .screw fasteners 14, and adapted to be removed from the chest10 to provide access into the chest and to the rod R and piston Aarranged in the cylinder O therein.

The piston rod R illustrated throughout the drawings is a typical orstandard slush pump piston rod and includes, an elongate body extendingthrough the stuing box 11 into the pump chest 10 1to include wi-thin thecylinder O, a forwardly convergent or tapered inner end portion 15within the cylinder O, and a threaded extension or shank 16 projectingforwardly from the forward terminal end of the said tapered portion 15.

The piston construction A that I provide includes, generally, a `stopcollar 17 engageable on the tapered extension 1'5 of the piston rod R, acarrying and retrieving hub I18 engageable around and clear of the rodto abut the stop collar, a piston body 19 carried by the hub to sealwith the stop collar and engage the wall of the cylinder O of the pumpP, and a follower or retainer 20 engageable on the extension 15 of therod R and on the hub 18 and adapted to retain the hub 118 engaged withthe stop collar 17, the piston body 19 engaged on the hub 18, and alsoto seal with the piston -body 19.

The piston body 19 provided by the present invention is an elongatecylindrical member with a smooth outer peripheral wall 21 adapted to beslidably engaged in the cylinder O of a slush pump or the like, withoppositely facing end walls 22 and a central longitudinal disposedopening 23 extending through the body from one to the other. The pistonbody is provided with outer uid actuated sealing lips 24 at each endthereof adapted to establish sealing engagement with the wall of thecylinder O, and inner iluid actuated sealing lips 25 at each en dthereof and adapted to establish sealing engagement with the stop collar17 and with the retainer or follower 20.

The outer sealing lips 24 at the ends of the piston body 19 arecircular, longitudinally disposed iin-like extensions of the peripheraland end walls 21 and 2.2 of the piston body and are established bypitching the outer peripheral wall 21 of the piston body 19longitudinally and radially inward from each end of the body andpitching the end wall 22 of the body19 longitudinally and radiallyinward from the outer peripheral edges thereof. The inner sealing lips25 at the yends of the piston body 19 adapted to establish sealingengagement with the stop collar 17 and the retainer 20, are establishedby longitudinally disposed annular iin-like projections about the innerperiphery of the body 19, defined by the longitudinal opening 23extending therethrough.

The piston body 19 is further provided with a suitable core 30 formed ofiron or otherfsuitable rigid material. The core 30 provides the pistonbody with sufficient strength and rigidity to withstand the severestresses and strains that are encountered in its normal operation in thecylinder of a pump, without tearing, pulling loose, or otherwisebecoming mutilated or rendered prematurely ineffective. v

The core 36 is a ilat annular member arranged in the piston body 19 tooccur midway between the ends thereof. The core 30 is of slightly lessoutsidediameter than the piston body 19, so that its outer periphery isinward of the outer peripheral wall 21 of the body. The inside diameterof the core 3i? is of substantially less diameter than the opening 23 inthe piston body 19 so that the core 30 projects inwardly into theopening to establish an annular inwardly projecting rib 31 deiiningforwardly and rearwardly facing shoulders 32 and 33 and a centrallongitudinal opening 34 substantially less in diameter than the openingZ3 extending through the body.

With the above relationship of parts, it will be apparent that the outercylinder engaging wall 21 of the piston body 19 is unobstructed and thatthere is no metal part'occurring therealong, that will engage and wearthe wall of the cylinder O when the piston construction A is operatedtherein. it will also be apparent that the portion of the coreprojecting into the opening 23 of the pistonbody 19 and establishing therib 31, provides a rigid member that can be advantageously engaged bythe hub 1S and clamped between the stop collar 17 and the retainer 2t).

lt has been found that when metal and rubber are bonded together, littleeffort is required to separate the rubber from the metal when tensionalforces are exerted therebetween, while great forces are required toseparate the metal and rubber through shearing action.

The core 39 provided by the present invention has a plurality ofcircumferentially spaced longitudinally disposed openings 35 extendingthrough the inner peripheral portion thereof, a plurality ofcircumferentially spaced rearwardly and outwardly opening recesses 36about the outer periphery thereof, and a plurality of forwardly andoutwardly opening recesses 37 about the outer periphery thereof andstaggered, or circumferentially offset from the said rearwardly openingrecesses 36. The core 30 also has forwardly and rearwardly projecting,longitudinally disposed annular ribs 38 on the sides thereof andarranged between the said openings 35 in the inner peripheral portion ofthe core and the recesses 36 and 37 in the outer peripheral portion ofthe core. The annular ribs 38 extend longitudinally of the piston body19 to occur between the outer peripheral wall 21 and the central opening23 of the piston body and terminate short of the end walls 22 thereof.

, lt will be apparent that the rubber, or rubber-like material, of whichthe piston body 19 is molded or cast, is bonded to the core 3i) andextends through the openings 35 in the core to establish inner tiemembers 35a integrally joining or tying the rubber material occurring atopposite sides of the core St) together and radially inward of theannular ribs 38 on the body. The annular ribs 38 extendinglongitudinally in the body 19 and projecting from the opposite sides ofthe core 30, provide radial stability for the body and stop or checkexcessive radial ilexure and pulling of the body away from the stopcollar 17 and retainer 20 of the piston construction as it isreciprocated in the cylinder O, which liexure and pulling, if notchecked, would result in rapid fatigue and tearing of the rubber ofwhich the body is formed.

The staggered or circumferentially offset, oppositely facing andoutwardly opening recesses 36 and 37 about the outer periphery of thecore 30 that I provide, establish increased longitudinally disposedbonding surfaces for the rubber about the outer periphery of the core.The added or increased surfaces established by the recesses 36 and 37 inthe core 3i? are adapted to overcome the longitudinal vforces that tendto pull the rubber from the core by providing additionallongitudinal'bonding surfaces that will transmit the longitudinal forcesexerted on and through the rubber piston body to the core throughshearing action.

It will be apparent that the opening 35 and ribs 38 of the core 30 alsoprovide longitudinal bonding surfaces for the rubber on the core, inaddition to the particular ends for which they are intended.

The outer peripheral portions of the core 30 between the recesses 36,occur adjacent the recesses 37 in the other or opposite side of the coreto establish bottoms in the recesses 36, which bottoms restrictexcessive longitudinal flow or movement of the rubber in the recesses 36when the piston body is in operation. In like manner the outerperipheral portions of the core between the recesses 36 occur adjacentand close the recesses 37 to restrict excessive longitudinal movement oriiow of the rubber occurring in the recesses 37 when the piston is inoperation.

The outer peripheral portion of the core between the recesses 36 and 37are provided with longitudinal openings 39 through which the rubber ofwhich the body is formed extends to establish outer tie members 39aintegrally joining or tying the rubber, or rubber-like material,occurring at opposite sides of the core together at points radiallyoutward of the annular ribs 38 on the body.

In the preferred carrying out of the invention, the circumferentialextent of the outer peripheral portions of the core occurring betweenthe recesses 36 and 37 is slightly less than the circumferential extentof the recesses, so that the edge portions of the recesses 36 and 37overlap and are in open communication with each other at their sideedges. With the above relationship of parts, the rubber occurring in therecesses 36 is integrally joined to the rubber in the recesses 37, whichjoinder further insures against separation or pulling apart of therubber occurring at opposite sides of the core and in the recesses.

From the above it will be seen that the core 30 provided by the presentinvention is highly effective in maintaining the piston body 19 inproper working position and is such that the molded rubber mass of whichthe body 19 is formed, will not tear olf or otherwise become disengagedfrom the core.

It is to be understood that the piston body 19 is re- Versible, that is,it can be turned end for end, and that the particular forward and rearends of the body referred v to above is for the purpose of illustrationonly.

The stop collar 17 provided by the present invention 1s an elongate bodyround in cross sectional configuration and is characterized by a centralforwardly convergent or tapered opening 41 adapted to receive and estab-I lish tight wedging engagement with the tapered end portion 15 of thepiston rod R. The stop collar 17 is provided with a at wall or face 42vat its forward end and a centrally located counterbore 43 in the face42 concentric with and surrounding the opening 41.

In the preferred carrying out of the invention the outer peripheral wall44 of the stop collar 17 is provided at its forward end with a portionof reduced diameter adapted to be slidably engaged in the opening 23 ofthe piston body 19 at the rear end thereof and engage the rearwardlyfacing shoulder 33 defined by the rib 31 in the body, and to establishan outwardly facing annular seat 45 adapted to cooperate with the innersealing lip 25 on the rear end of the piston body 19.

'I'he hub 18 is an elongate cylindrical member adapted to carry thepiston body 19 and to facilitate removal of the body from within thecylinder of a pump. The hub 18 is provided with a central, longitudinalopening 50 extending therethrough adapted to freely receive and pass thetapered end portion 15 of the piston rod R. The hub 1-8 corresponds indiameter and longitudinal extent with, and is slidably engageable in,the opening 34 in the rib 31 established by thecore 30 in the pistonbody 19. The hub 18 is provided with an enlargement or head 51 thecollar and around the rod when the piston construction is assembled. Thehead 51 on the hub 18 establishes a forwardly facing stop shoulder 52projecting radially outward from the peripheral wall of the hub to occurin a substantially parallel plane with the forwardly facing end face 42on the stop collar 17 when the head is engaged in the counterbore 43.The hub 18 further includes a forward end face 53 and an externallythreaded extension 54 of reduced diameter projecting forwardly from theend face 53 to extend beyond the forward end of the rod and overlie aportion of the extension 16 on the rod.

It will be apparent from the above, that when the stop collar 17, hub 18and piston body 19 are assembled the rear end lof the piston body 19overlies and seals with the forward end portion of the stop collar andthe rearwardly facing shoulder 33 of the rib 31 in the body 19established by the core 30, engages the forward end face 42 on the stopcollar and the forwardly facing shoulder 52 on the retrieving andcarrying hub 18. The forwardly facing shoulder 32 defined by the rib 31and the forward end face 53 on the hub 18 occur in a common plane andare ush with each other.

The follower or retainer 20 that I provide is adapted to be engaged withthe hub 18 to retain the piston body 19 thereon and also to engage thethreaded shank 16 of the rod R to maintain the hub 18 and the pistonbody 19 on the rod and in tight butting engagement with the stop collar1'7.

The retainer 20 is provided with an elongate cylindrical rear endportion 60 having a longitudinally disposed annular sealing face 61slidably engageable in the opening 23 in the piston body from theforward end thereof and adapted to establish sealing engagement with theforward inner sealing lip 25 on the body, a flat rearwardly facing endwall 62 adapted to establish flat butting engagement with the forwardlyfacing shoulder 32 defined by the rib 31 in the piston body and thefront end face 53 on the hub. The rear end portion 60 of the retainer isfurther provided with a central, internally threaded longitudinallydisposed socket opening 63 adapted to receive and engage the threadedextension 54 on the hub to maintain the hub 18, piston body 19, andretainer 20 in tight assembly. The retainer 20 is further provided witha forward end portion 65 with a central internally threaded opening 66extending therethrough and adapted to receive and engage the threadedextension 16 on the end of the rod R to hold the hub 18 and piston body19 in engagement with the stop collar 17.

In practice, the stop collar 17 is independently or separately appliedto the tapered end portion of the piston rod R in the manner illustratedin Fig. 3 of the drawings, to have tight wedging engagement therewith,and need never be removed therefrom. While the hub 18, piston body 19and retainer 20 are engaged together in the manner illustrated in Fig. 4of the drawings to form a sub-assembly of parts, prior to insertion andengagement of the said parts into the pump cylinder and with the rod Rand collar 17. With the above relationship of parts it will be apparentthat the various parts of my piston construction forming thesub-assembly referred to above, can be advantageously assembled ordisassembled, and worn or damaged parts repaired or replaced, at alocation removed from the pump.

It will also be apparent from the above that the piston construction Athat I provide can be advantageously engaged on the piston rod R and inthe cylinder O of the slush pump P, through the head end of the pumpchest 10 by simply removing the head 13 therefrom, and that the pistonrod R need not be pulled or removed from the pump.

In the preferred carrying out of the invention, the rearmost end of thehead 51 on the hub 18 is provided 6 with a tool engaging slot 56, andthe forward end portion 65 of the retainer20 is provided with aplurality of tool engaging flats 67 about its peripheral wall, tofacilitate assembly or disassembly of the structure.

To facilitate insertion or removal of the above mentioned sub-assemblyof parts from within the cylinder O, l provide a suitable pulling tool70 having a threaded body 71 engageable in the threaded opening 66 inthe rear end portion 65 of the retainer 20, an elongate stem 72projecting forwardly from the body 71, and a suitable tool engaging head73 on the forward terminal end of the stem and accessible at theexterior of the cylinder O, or if desired at the exterior of the chest10 of the pump.

To apply the subassembly of parts, shown in Fig. 5 of the drawings, tothe piston rod R upon which the stop collar 17 is initially engaged, thepiston rod R is moved to its foremost position or stroke, thesubassembly is then engaged in the cylinder from the open forward endthereof (see Fig. 5) so that the threaded extension 16 of the rod entersthe threaded opening 66 in the retaincr 20, whereupon rotation of thesubassembly by means of a suitable tool engaged with or on the flats 67on the portion 65 of the retainer, establishes threaded engagementbetween the retainer and the rod and advances the subassembly of partsinto tight engagement with the stop collar 17 on the rod and into thecylinder O of the pump P. In practice, a suitable lock nut is engaged onthe outer terminal end of the rod extension 16 to abut the outer end ofthe retainer 20 to maintain the retainer and extension 16 in tightthreaded engagement.

To remove the subassembly, or disassemble the piston construction A, itis only necessary to reverse the above procedure, that is, remove thelock nut 80 and unscrew the retainer 2i) from the end of the piston rodR. It will be apparent that upon removal or unscrewing of the retainer20 from the extension of the piston rod R, the retrieving and carryinghub 18 and piston body 19 carried thereby are Withdrawn from engagementwith the piston rod and stop collar 17, whereupon the pulling tool 70that I provide can, if necessary, be engaged in the retainer 20, in themanner illustrated in Fig. 3 of the drawings, and the subassembly ofparts withdrawn from within the lcylinder O of the pump.

At no time, during application or removal of the piston construction Aonto the piston rod R, is the rod rotated or moved longitudinally in thepump. The above feature is highly significant since it prevents damageand misalignment of the rod and packing in the stuffing box 11 in thepump.

Having described only a typical preferred form and application of myinvention, I do not wish to be limited or restricted to the specificdetails herein set forth, but wish to reserve to myself any Variationsor modifications that may appear to those skilled in the art and fallwithin the scope of the following claims.

Having describedvmy invention, I claim:

1. A pump piston construction adapted to be engaged on the end of apiston rod having a thread extension including, a cylindrical stopcollar with a ilat front face releasably engaged on the rod, an elongatecylindrical hub smaller in diameter than the collar and freelyengageable around the rod to abut the face on the collar, an elongatecylindrical piston body formed of rubber, an inwardly projecting annularrib in the body midway between the ends thereof and slidably engaged onand surrounding the hub, a forwardly projecting threaded extension onthe hub, an elongate cylindrical retainer with a rear end portioncorresponding in diameter with the stop collar and threadedly engagingthe extension on the hub and a forward end portion threadedly engagingthe eX- tension on the rod, the retainer holding the hub and body intight assembly and in fixed position on the rod and against the collar,and the body slidably receiving and sealing around the collar and theretainer.

2. A pump piston construction adapted to be engaged on the end of apiston rod having a forwardly tapered end portion anda forwardlyprojecting threaded extension including, a cylindrical stop collar witha central forwardly convergent longitudinal opening and a llat frontface releasably engaged on the tapered portion of the rod, an elongatecylindrical hub with a central longitudinal opening and freely receivingthe said portion of the rod to abut the face on the collar, the hubbeing smaller in diameter than the collar, an elongate cylindricalpiston body formed of rubber, an inwardly projecting annular rib in thebody midway between the ends thereof and surrounding the hub, aforwardly projecting extension on the hub, an elongate retainer with arear end portion corresponding in diameter with the stop collar andthreadedly engaged on the extension on the hub and a forward end portionthreadedly engaged on the extension on the rod, the retainer holding thehub and body in tight assembly, and the assembly tight on the rod andagainst the collar, and the body slidably receiving and sealing aroundthe collar and the retainer.

3. A pump piston construction adapted to be engaged on the end of apiston rod having a thread extension including, a cylindrical stopcollar with a flat front face releasably engaged on the rod in ixedposition thereon, an elongate cylindrical hub smaller in diameter thanthe collar and freely engaged around the rod to abut the face on thecollar, a radially elongate cylindrical piston body formed of rubber, aninwardly projecting annular rib in the opening in body midway betweenthe ends thereof and slidably engaging and surrounding the hub, aforwardly projecting externally threaded extension on the hub, anelongate retainer with a rear end portion corresponding in diameter withthe stop collar and having a rearwardly opening internally threadedsocket opening receiving the extension on the hub and a forward endportion with an internally threaded longitudinal opening receiving theextension on the rod, the retainer holding the hub and body in tightassembly and the assembly on the rod and tight against the collar, andthe body slidably receiving and sealing around the collar and theretainer.

4. A pump piston construction adapted to be engaged on the end of apiston rod having a forwardly tapered end portion and a forwardlyprojecting threaded extension including, a cylindrical stop collar witha central forwardly convergent longitudinal opening and a flat frontface releasably engaged on the tapered portion of the rod in fixedposition thereon, an elongate cylindrical hub with a centrallongitudinal opening freely engageable around the said portion of therod to abut the face on the collar, the hub being smaller in diameterthan the collar, an elongate cylindrical piston body formed of rubber, aradially inwardly projecting annular rib in the opening in the bodymidway between the ends thereof and slidably engaged on and surroundingthe hub, a forwardly projecting externally threaded extension on thehub, an elongate retainer with a rear end portion corresponding indiameter with the stop collar and having a rearwardly opening internallythreaded longitudinal opening receiving the extension on the rod, theretainer holding the hub and body in tight assembly and the assembly onthe rod and in tight engagement against the collar, and the bodyslidably receiving and sealing `around the collar and the retainer.

5. A pump piston construction adapted to be engaged on the end of apiston rod having a forwardly tapered end portion and a forwardlyprojecting threaded extension including, a cylindrical stop collarengageable on the rod in fixed position thereon andhaving a centralforwardly convergent longitudinal opening receiving the tapered portionof the rod, a flat front face and a forwardly opening counterbore in theface, an elongate cylindrical hub smaller in diameter than the collarand having a central longitudinal opening larger in diameter than therod and receiving the tapered portion of the rod, a head on the rear endof the hub and engageable in the counterbore in the collar and defininga forwardly facing shoulder flush with the face on the collar, anelongate cylindrical piston body formed of rubber, an inwardlyprojecting annular rib in the body midway between the ends thereofcorresponding in longitudinal extent with Vand surrounding the hub, 'aforwardly projecting extension on the hub, an elongate retainer with arear end portion corresponding in diameter with the stop collar, andreleasably engaging the extension on the hub and a forward end portionreleasably engaging the extension on the rod, the retainer holding thehub and body in tight assembly and the assembly on the rod and in tightengagement against the collar, and the body slidably receiving andsealing around the collar and the retainer.

6. A pump piston construction adapted to be engaged on the end of apiston rod including, a cylindrical stop collar engageable on the rod, acylindrical hub smaller in diameter than the stop collar and engageablearound the rod and against the stop collar, a cylindrical retainercorresponding in diameter with the stop collar and threadedly engaged onthe hub and on the rod, lan elongate cylindrical rubber piston body witha central longitudinal opening slidably receiving the stop collar andthe retainer, and having a metallic core intermediate its ends andprojecting inwardly in the opening to occur between the stop collar andthe retainer and slidably receiving and surrounding the hub, the corehaving circumferentially spaced longitudinally disposed openingsextending therethrough and receiving rubber tie members extendingbetween the body occurring at opposite sides of the core.

7. A pump piston construction adapted to be engaged on the end of apiston rod including, a cylindrical stop collar engageable on the rod infixed position thereon, a cylindrical hub smaller in diameter than thestop collar and freely engageable around the rod and against the stopcollar, a cylindrical retainer corresponding in diameter with the stopcollar and threadedly engaged on the hub and on the rod, a-n elongatecylindrical rubber piston body with a central longitudinal openingslidably receiving the stop collar at one end and the retainer at theother end, and having a metallic core intermediate its ends andprojecting radially inwardly to occur between the stop collar and theretainer and surrounding the hub, the core having circumferentiallyspaced radially outwardly opening notches about its outer periphery toestablish longitudinally disposed bonding surfaces for the rubber body.

8. A pump piston construction adapted to be engaged on the end of lapiston rod including, a cylindrical stop collar engageable on the rod inlixed position thereon, a cylindrical hub smaller in diameter than thestop collar and freely engageable around the rod and against the stopcollar, a cylindrical retainer corresponding in diameter with the stopcollar and ithreadedly engaged on the hub and on the rod, lan elongatecylindrical rubber piston body with a central longitudinal openingslidably receiving and sealing around the stop collar and the retainer,and having a metallic core intermediate its ends and projecting radiallyinwardly in the opening to occur between the stop collar and theretainer and slidably engaged on and surrounding the hub, the corehaving circumferentially spaced longitudinal openings receiving tiemembers integrally joining opposite ends of the body together, yandcircumferentially spaced outwardly opening notches providinglongitudinal bonding surfaces for the rubber body on the core.

9. A pump piston construction adapted to be engaged on the end of apiston rod including, a cylindrical stop collar engageable on the rod infixed position thereon, a cylindrical hub smaller in diameter :than thestop collar and freely engageable around the rod and against the stopcollar, a cylindrical retainer ycorresponding in diameter with the stopcollar and threadeidly engaged on the hub and on the rod, yan elongatecylindrical rubber piston body with a central longitudinal openingsllidably receiving and sealing around the stop collar and the retainer,and having a flat radia-lly disposed metallic core intermediate its endsand projecting radia'lly inwardly in the opening to occur between thestop collar and the retainer and slidably engaged on `and surroundingthe hub, the core having annular stiffening ribs projectinglongitudinally from opposite sides of the core to occur with the bodyand surrounding the collar and the retainer in spaced relationshipthereto.

10. A pump piston construction adapted to be engaged on the end of apiston rod including, a cylindrical stop collar engageable on the rod intight xed engagement therewith, a cylindrical hub smaller in diameterthan the stop collar and freely engageable around the rod and Iagainst:the stop coll-ar, a cylindrical retainer corresponding in diameter withthe stop collar and threadedly engageable with the hub and with the rod,an elongate cylindrical rubber piston body with a central longitudinalopening slidably receiving the stop colllar and the retainer from itsopposite ends, and having a at radially disposed annular metallic coreintermedi-ate its ends and projecting radially inwardly to occur betweenthe stop collar and the retainer :and surrounding the hub, the corehaving circumferential'ly spaced longitudinal openings receiving tiemembers extending between the body occuring at opposite sides of thecore land having annular stiiening ribs projecting longitudinally fromopposite sides of the core to occur within the body and overlying thecollar and the retainer.

11. A pump piston co-nstruction adapted to be engaged on the end of apiston rod including, a cylindrical stop collar engageable on the rod intight fixed engagement therewith, a cylindrical hub smaller in diameterthan the stop [collar and freely engageable around the rod and againstthe stop collar, a cylindrical retainer corresponding in diameter withthe stop collar and threadedly engageable with the hub and on the rod,an elongate cylindrical rubber piston body with a central longitudinalopening slidably receiving and sealing around the stop collar and theretainer, and having a fiat annular radially disposed metallic coreintermediate its ends and projecting radially inwardly in the opening inthe body to occur between the stop collar and the retainer and slidablyengaged on and surrounding the hub, the core having annular stiifeningribs projecting longitudinally from opposite sides of the core to occurwithin the body and overlying the collar and the retainer, and havinginner and outer rows of circumferentially spaced longitudinal openingsreceiving tie members extending between the body occurring at oppositesides of the core the said inner and outer rows of openings occurring atopposite sides of the annular ribs.

l2. A pump piston construction adapted to be engaged on the end of apiston rod including, a cylindrical stop collar engageable on the rod intight xed engagement therewith, a cylindrical hub smaller in diameterthan the stop collar and freely engageable around the rod and againstthe stop collar, a cylindrical retainer corresponding in diameter withthe stop collar and threadedly engageable with the hub and with the rod,an elongate cylindrical rubber piston body with a central longitudinalopening slidably receiving the stop collar and the retainer at itsopposite ends, and having a ilat annular `radially disposed metalliccore interme- -diate its ends and projecting inwardly to occur betweenthe stop collar and the retainer and surrounding the hub, the corehaving circumferentially spaced forwardly and outwardly opening notchesand circumferentially spaced rearwardly and outwardly opening notchesabout its outer periphery to establish longitudinal bonding surfaces forthe rubber body, and having annular stiiening ribs projectinglongitudinally from opposite sides of the core to occur within the body.

13. A pump piston construction adapted to be engaged on the end of apiston rod including, a cylindrical stop collar engageable on the rod infixed position thereon, a cylindrical hub smaller in diameter than thestop collar and freely engageable around the rod and against the stopcollar, a cylindrical retainer corresponding in diameter with the stopcollar and threadedly engageable on the hub and on the rod, an elongatecylindrical rubber piston body with a central longitudinal openingslidably receiving the stop collar and the retainer at its oppositeends, and having a at annular radially disposed metallic coreintermediate its ends and projecting radially inwardly in the opening inthe -body to occur between vthe stop collar and the retainer andsurrounding the hub, the core having circumferentially spacedlongitudinal openings about the inner peripheral portion and receivingtie members integrally joining `opposite ends of the body together,circumferentially spaced outwardly opening notches about the outerperiphery providing longitudinal bonding surfaces for the rubber body onthe core, and annular stiffening ribs between the notches and theopenings and projecting from opposite sides of the core.

14. A pump piston construction adapted to be engaged on the end of apiston rod including, a cylindrical stop collar engageable on the rod infixed position thereon, a cylindrical hub smaller in diameter than thestop collar with a straight outer peripheral wall and freely engageablearound the rod and against the stop collar, a cylindrical retainer witha straight outer peripheral wall and corresponding in diameter with thestop collar and threadedly engageable with the hub and the end of therod, an elongate cylindrical body formed of rubber and having an outercylinder engaging surface, a central longitudinally disposed openingslidably receiving the stop collar and the retainer, an annular metallicreinforcing core in the body with a portion projecting radially inwardlyinto the opening in the body to establish a rib in the body intermediateits ends and occurring between the collar and the retainer and slidablyengaging an-d surrounding the hub, the body having outer fluid actuatedsealing lips at each end thereof to seal with a cylinder wall and innerfluid actuated sealing lips at each end thereof and sealing with theouter peripheral walls of the collar and the retainer.

References Cited in the file of this patent UNITED STATES PATENTS1,833,920 Steirly Dec. 1, 1931 1,849,096 Kinele Mar. 15, 1932 2,163,162Wells June 20, 1939 2,277,501 Murray Mar. 24, 1942 2,279,238 Larson Apr.7, 1942

